Atoms, Element And the periodic Table

  • 500

    emocritus; Ancient Greece

    Democritus introduces the philosophical concept of the atom in the universe.
  • May 28, 1000

    Tin (Se)

    Tin (Atomic number 50) was discovered by the anceients in the early times. Health affects of Tin: Humans can absorb tin bonds through food, breathing and through the skin. It can cause dizziness, eye and skin irritation, Headaches, and liver damage.
  • May 28, 1000

    Sulfur (S)

    Noone knows the exact date sulfur was discovered but scientist agree it would of been around 2000B.C. Atomic number 16 HEALTH EFFECTS all living things need sulfur in order to live
  • May 29, 1000

    Carbon (C)

    Carbon was discovered by the ancients and it is unknown the exact time it was discovered. Carbons atomic number is 6 and it contains a low toxity.
  • May 29, 1000

    Lead (Pb)

    Leads atomic number is 82. Lead was also discovered by the Egyptians, Babylonians, Assyrians and Chinese. Lead is dangerous to humans as it is poisonous. If you intake high amounts you may become very ill.
  • May 29, 1000

    Silver (Ag)

    Silver was discovered by the Ancients.Silver can cause serveral problems
    Eye Contact: Corneal Injury.
    Skin Contact: Skin Irritation.
    Inhale: Dizziness, headaches or trouble breathing.
  • May 29, 1000

    Mercury (Hg)

    Mercury was discovered in ancient times. Atomic number 80 iIt is a very toxic element that can alter genetic and enzyme systems and damage the nervous system.
  • May 29, 1250

    Arsenic (As)

    Aresinc was dicovered during the bronze age by Albertus Magnus in 1250.
    Health effects: Arsenic is one of the most toxic elements that can be found.high exposure to arsenic can cause infertility and miscarriages within women, and it can cause skin disturbances, declined resistance to infections, heart problems and brain damage.
  • Term 'electricius'

    1600 treatise De Magnete, the English scientist William Gilbert coined the New Latin term electricus, to refer to this property of attracting small objects after being rubbed.
  • Phosphorus (P)

    Phosphorus was discovered in 1669 in Germany by Hennig Brand.
    Health Effects: severe effects on the kidneys, liver, cardiovascular system, and central nervous system .
    Inhalation exposure has resulted in respiratory tract irritation and coughing in humans.
  • Newton

    Newton proposes that atoms are small solid substances constantly in motion in a 'mechanical universe' (an infinitely structured universe). This 'mechanical universe' is an important idea of Newton's, related to his explanation of the cosmic order.
  • Antimony (Sb)

    A french chemisist Nicolas Lémery discovered Antimony. It has an atomic number of 51
    Health Effects: Exposure for long peiods of time can cause irritation of the eyes, skin and lungs.As the exposure continues more serious health effects may occur, such as lung diseases, heart problems, diarrhea, and severe vomiting
  • Platinum (Pt)

    Was discovered by Julius Scaliger.c
    Health Effects: Platinum as a metal is not very dangerous, but platinum salts can create/cause many health effects, such as: DNA alterations, Cancer, Allergic reactions of the skin and the mucous membrane, Damage to organs, such as intestines, kidneys and bone marrow, and Hearing damage
  • Cobalt (Co)

    Was discovered by George Brandt.
    Health Effects: Cobalt can cause sterility, hair loss, vomiting, bleeding, diarrhoea, coma and even death. This radiation is sometimes used with cancer-patients to destroy different types of tumors. These patients also suffer from hair loss, diarrhea and vomiting
  • Zinc (Zn)

    Zinc is a metallic chemical element. Zinc was found in 1746 by Andreas Marggraf. The name comes from the German word zin (meaning tin). It's atomic number is 30. It belongs to the family of other metals. Some health effects of zinc are that when someone doesn't get enough zinc they begin to loose their apetitie, decrease of taste and smell and slow wound healing and skin sores. When people absorb too of this element they are likely to experience stomach cramps.
  • First Elements

    Antoine Lavoisier made the first extensive list of elements. The list featured 33 different elements which were classified between metals and non-metals
  • First useful Atomic Theory

    Around 1803, John Dalton (1766-1844) developed the first useful atomic theory of matter. He imagined the atom as a sphere full of an electrically positive substance mixed with negative electron.
  • Main points of Daltons Atomic theory

    Elements are made of extremely small particles called atoms.
    Atoms of the same element are identical in size, mass, and other properties; atoms of different elements differ in size, mass, and other properties.
    Atoms of different elements combine in simple whole-number ratios to form different chemical compounds.
    In chemical reactions, atoms are combined, separated, or rearranged.
  • Jakob Berzelius

    Jakob Berzelius developed a table of atomic weights.
  • Elements Represented as Letters

    Jakob Berzelius developes a table of atomic weights for several elements. This was the first table the represented different elements with letters.
  • Johann Dobereiner

    He proposed the Law of Triads: the center element in some instances had an atomic weight that was the average of the other two members. He began grouping elements based on similarities. He discovered that calcium (atomic weight 40), strontium (atomic weight 88) and barium (atomic weight 137) had similar properties, and that strontium had an atomic weight halfway between calcium and barium. He discovered it was the same for lithium, sodium, and potassium.
  • Periodic table editting Jean- Baptiste

    Jean-Baptiste Dumas published work in 1857 describing relationships between various groups of metals. Although various chemists were able to identify relationships between small groups of elements, they had yet to build one scheme that encompassed them all.
  • Alexandre Emile Beguyer de Chancourtois

    Published the first list of elements that was ordered by increasing atomic mass. Elements with similar properties went on the same row. His findings were ignored until Mendeleev.
  • John Newlands

    He ordered the 62 known elements at the time in order of the increasing atomic weight. He noticed that after eight elements occurred, the ninth element displayed similar properties to the first one. He wrote a paper saying that each element showed similar properties to the eighth element following it. He created the Law of Octaves: Elements exhibit similar behaviour to the eighth element following it in the table.
  • Dmitri Meldeleev

    Ordered elements by atomic weights and properties. The table contained 17 columns, two partial periods with 7 elements in each and two nearly complete periods.
  • mandeleev revises the periodic table

    In 1871 Mendeleev revised the 17-group table with eight columns (the eighth group consisted of transition elements). This table exhibited similarities not only in small units such as the triads, but showed similarities in an entire network of vertical, horizontal, and diagonal relationships.
  • G.J Stoney; Ireland

    Stoney proposes that electricity is made up of negative particles called electrons. This introduces the idea of electrons, linking it to electricity (hence establishing that electrons have a charge) and its structure.
  • Lord Rayleigh, William Ramsey

    Argon is discovered. It was chemically inert, not fitting into any of the groups in Mendeleev's periodic table. William Ramsey discovered the rest of the inert gases and put them in Mendeleev's periodic table. (Inert gases have been renamed and are now called the noble gases.)
  • Thomson discovers the electron

  • DIscovery of Neon

    Neon was discovered by Sir William Ramsay, a Scottish chemist, and Morris M. Travers, an English chemist, shortly after their discovery of the element krypton in 1898. Like krypton, neon was discovered through the study of liquefied air. Although neon is the fourth most abundant element in the universe, only 0.0018% of the earth's atmosphere is neon.
  • Ernest Rutherford

    Rutherford discovers protons.
    Ernest Rutherford who performed many experiments to explore radioactivity did an experiment in which he discovered that the atom must have a concentrated positive center charge that contains most of the atom's mass.He suggested that the nucleus contained a particle with a positive charge the proton
  • Rutherford discovers the nucleus

    After the discovery of the electron, it was realized that there must be positive charge centers within the atom to balance the negative electrons and create electrically neutral atoms. Rutherford's discovery of the nucleus demonstrated that these positive charges were concentrated in a very small fraction of the atoms' volume.
  • Henry Moseley

    He subjected known elements to x-rays and found a relationship between x-ray frequencies and number of protons. Moseley arranged elements by atomic numbers, not mass, which removed some of the inconsistencies with Mendeleev's table.
  • Changing Elements

    Rutherford discovered that he could change one element into another by striking it with energetic alpha particles (which we now know are just helium nuclei).
  • Rutherford proton explaination

    In the early 1920's Rutherford and other physicists made a number experiments, transmuting one atom into another. In every case, hydrogen nuclei were emitted in the process. It was apparent that the hydrogen nucleus played a fundamental role in atomic structure, and by comparing nuclear masses to charges, it was realized that the positive charge of any nucleus could be accounted for by an integer number of hydrogen nuclei. By the late 1920's physicists were casually referring to hydrogen nuclei
  • Bohr; Denmark

    He develops an explanation of atomic structure that shows the connections of the Periodic Table, and recognising the trends and similarities that several elements share with others. Bohr creates a model of the atom, built up of successive orbital shells of electrons
  • James Chadwick

    It is remarkable that the neutron was not discovered until 1932 when James Chadwick used scattering data to calculate the mass of this neutral particle.
  • James Chadwick; England

    Using alpha particles in his experiment, Chadwick discovers the neutron is in the nucleus of the atom. He notes that the neutron that he discovers has a mass close to the proton of the element's atom.
  • Francium (Fr)

    (Atomic Number 87), the Last Discovered Natural Element
    Due to its instability and rarity, there are no commercial applications for francium.
    It has been used for research purposes in the fields of biology
  • Glenn Seaborg

    He experimented with plutonium and discovered the transuranium elements, numbers 94-102 and changed the periodic table by putting them at the bottom.
  • Dmitri Mendeleev

    He changed the table, giving it 8 columns. This table showed diagonal, vertical and horizontal relationships between elements. It contained gaps where Mendeleev predicted new elements would be discovered.
  • Natrual occuring elements

    2011 it was found that all the elements up to californium can occur naturally as trace amounts in uranium ores by neutron capture and beta decay.
  • Mendekeeve updated periodic table

    In 1871, Mendeleev published an updated form of periodic table , as well as giving detailed predictions for the elements he had earlier noted were missing, but should exist. These gaps were subsequently filled as chemists discovered additional naturally occurring elements.